German Patent Application No. 41 21 310 describes a fuel injector which has a valve-seat member on which a fixed valve seat is formed. A valve-closure member, axially movable in the injector, interacts with this valve seat formed in the valve-seat member. Contiguous to the valve-seat member in the downstream direction is a flat jet-aligning plate, in which, facing the valve seat, provision is made for an H-shaped depression as an inlet area. Contiguous to the H-shaped inlet area in the downstream direction are four spray-discharge orifices, so that a fuel to be sprayed can be distributed via the inlet area right up to the spray-discharge orifices. In this case, the flow geometry in the jet-aligning plate is not intended to be influenced by the valve-seat member. Rather, a flow passage downstream of the valve seat in the valve-seat member is designed to be so wide, that the valve-seat member has no influence on the orifice geometry of the jet-aligning plate.
A lack of influence of the valve-seat member on the orifice geometry of an orifice plate arranged at a fuel injector applies also to fuel injectors which are described in U.S. Pat. No. 4,699,323 or in European Patent No. 0 310 819. In these patents, the orifice plates have functional planes with different orifice geometries; however, an overlap of the inlet areas of the spray orifices in the orifice plate by the valve-seat member is in no way desired or allowed.
German Patent Application No. 196 07 277 describes a fuel injector having an orifice plate which has a plurality of functional planes exhibiting different orifice geometries. The individual functional planes of the orifice plate are built up on one another by galvanic metal deposition (multilayer electroplating). In this injector as well, the valve-seat member should never limit or overlap the inlet openings in the upper functional level of the orifice plate.